# How many moles of solute are in 250 mL of 2.0M CaCl_2? How many grams of CaCl_2 is this?

Aug 4, 2016

The solution contains 0.50 mol or 55 g of ${\text{CaCl}}_{2}$.

Moles of ${\text{CaCl}}_{2}$

You know there are 2.0 mol of ${\text{CaCl}}_{2}$ in 1 L of solution.

In 250 mL of solution there are

${\text{0.250" cancel("L soln") × "2.0 mol CaCl"_2/(1 cancel("L soln")) = "0.50 mol CaCl}}_{2}$

Mass of ${\text{CaCl}}_{2}$

The mass of 1 mol of ${\text{CaCl}}_{2}$ is

$\text{(40.08 + 2 × 35.45) g" = "(40.08 + 70.90) g" = "110.98 g}$.

So the mass of ${\text{0.50 mol of CaCl}}_{2}$ is

${\text{0.50" cancel("mol CaCl"_2) × "110.98 g CaCl"_2/(1 cancel("mol CaCl"_2)) = "55 g CaCl}}_{2}$